I can't find a good sized one. I got one at Walmart but it's pretty tiny. I went ahead and set everything up in it just to see if I could get it running and I'm working on getting the temps regulated. I saw where some have asked at Walmart for the coolers they ship the fishing worms in, but our Walmart has HORRIBLE customer service. Asking anything there is like asking a magic 8 ball. The workers are totally clueless. I think I might ask at Petsmart. If I have no luck, do you think a liquor store or a gas station would sell a larger styrofoam cooler? I could just buy a regular plastic cooler but I don't know how to cut into it and my DH has been busy building my second coop all weekend...he's iffy about me building an incubator in the first place. He keeps saying my plan to get 6-10 hens is escalating and out of control. Can't imagine where he would get an idea like that. Humph. (I have about 30 birds right now. and we got ducks too...) Somehow I don't think he'd be too excited to have to carve into a cooler for me. He also would not want me to play with his tools, as I am known for creating disasters.